Transmission



F. J. WINCHELL TRANSMISSION April 19, 1960 4 Sheets-Sheet l OriginalFiled July 25, 1956 EN@ X egg@ g F. J. WINCHELL April 19, 1960TRANSMISSION 4 Sheets-Sheet 2 Original Filed July 25, 1956 A TTOPNE Kca/ cf lake/9919' F. J. WINCHELL TRANSMISSION N.. @Q N?. u A 1 www .w .nw A .mx NN April 19, 1960 Original Filed July 25. 1956 ATTORNEK April19, 1960 F. .1. wlNcHELL 2,932,989

TRANSMISSION Original Filed July 25, 1956 4 Sheets-Sheet 4 INVENTORATTOANK United States Patent O TRANSMISSIN Frank J. Winchell, BloomfieldHills, Mich., assigner to General Motors Corporation, Detroit, Mich., acorporation of Delaware Original application July 25, 1956, Serial No.600,022.

Divided and this application September 16, 1957, Serial No. 634,345

This is a division of application of SN. 600,022 filed July 25, 1956.

This invention relates to improvements in the construction, arrangement,and control system in transmissions embodying hydrodynamic torquetransmitting devices which drive gearing for driving a power outputshaft at various speed ratios. The torque transmitting device may be atorque converter and the transmission may be used for driving a motorvehicle.

Hydrodynamic torque converters can be readily designed to provide anypractical degree of torque multiplication on starting, but if thestarting torque ratio is sufficiently high, the torque delivered by theturbine or output member may decrease too rapidly to be practical as theturbine starts to turn, and vanishes at an impractically low turbinespeed. This provides poor acceleration of the vehicle and may providetoo little torque as the device approaches coupling or one-to-one speedratio. On the other hand, the turbine can be constructed to provideacceptable coupling characteristics when the load reaches approximatelyimpeller speed, but this is done at a sacrifice of starting or stalltorque and at the sacrifice of accelerating torque in the middle rangesof car speed.

The considerations have resulted in the design and construction oftorque converters having various arrangements of several turbines ofdilerent torque characteristics, with or without torque multiplyinggearing. While these have been satisfactory within their inherentlimitations, they have had the disadvantage that they do not sustainadequate torque multiplication during intermediate speed ranges of thevehicle, which makes sluggish cars and makes it impractical, Withoutchanging gears, to obtain the so-called passing gear by which is meant asudden increase of torque ratio at any car speed throughout a wide rangeof car speeds.

'I'his invention seeks to overcome these and other disadvantages ofknown hydrodynamic transmissions and to provide a transmission whichchanges torque ratio smoothly and continuously, to improve theeliiciency of torque converters by providing a torque converter whichhas a high starting ratio and maintains a higher torque ratio than wasformerly possible during acceleration to one-to-one drive. lTheinvention also seeks to provide improved and simplified means forincreasing the torque ratio at any car speed.

Any torque converter turbine has the inherent characteristic ofproviding diminishing torque multiplication as the turbine speedincreases toward impeller speed as long as there is no turbine ahead ofthe turbine in question in the liquid stream from the impeller, whichother turbine is delivering torque thus influences the turbine underconsideration. This invention combines a series of turbines, each ofdifferent torque characteristics, in such a Way that as the torquemultiplication or torque ratio of one turbine decreases, the torquemultiplications of downstream turbines increase. If a sufficient numberof such turbines is provided, then while the turbines of the series aresuccessively fading out, that is their torque multiplications aredecreasing toward zero, the downstream turbines are increasing theirtorque ratios. In this way the torque ratio of the torque converter as awhole decreases toward coupling much more slowly than heretofore andstays at practically high values over long periods of acceleration ofthe vehicle. This provides an easily maneuverable and responsive vehicleof high performance.

This invention also provides means for increasing the range of torqueratio of one or more of the turbines at any `car speed to provideacceleration in emergencies or for a passing gear. This may be done, forexample by changing the angle of reaction blades, if such are used.

The invention also includes improved arrangements of gearing especiallyhelpful in achieving the foregoing objects, as well as improved controlsystem including improved timing arrangements which assure the smoothapplication of friction devices which establish various combinations ofgearing.

It is a specific object of the invention to improve the operation ofgearing as shown in the application for U.S. Patent S.N. 600,022 filedJuly 25, 1956 by insuring the positive and reliable operation of certainover-running clutches by which various elements of the hydrodynamictorque converters are connected to the drive train.

The foregoing and other objects and advantages of the invention will beapparent from the annexed description and from the accompanyingdrawings, in which:

Fig. l is a schematic representation of one form of transmissionembodying the invention, this being half of a symmetrical section alongthe axis;

Fig. 2 is a chart of the control conditions showing how the variousdrive conditions are established;

Figs. 3 and 3A together constitute one-half of a symmetrical,longitudinal section of the actual structure of a transmission embodyingone form of the invention;

Fig. 4 is an enlarged section taken as Figure 3A is taken of afree-Wheel device;

Fig. 5 is a section on the line 5 5 of Fig. 4;

Fig. 6 is a perspective of a portion of the free-wheel device; and

Fig. 7 is a perspective of a sprag or locking element of the free-wheeldevice.

Referring to Fig. l, the transmission includes an input shaft l0 drivinga hydrodynamic torque converter 12 which drives planetary forward andreverse reduction gearing ld connected to a nal output or drive shaft15. The torque converter itself may be constructed and arranged asdescribed -below and includes a pump or impeller l of generally knownform represented diagrammatically in Fig. 1 by a single blade i8 rotatedby the input shaft 10 and circulating liquid in a closed toroidal pathwhich includes a series of turbines, preferably three, and a reactionmember or guide wheel. The first turbine Tl, represented by a singleblade 2l, the second turbine T2, represented by a single blade 22, whichreceives oil from the rst turbine T1, and a third turbine T3,represented by a single blade 23, which receives oil from the turbine T2and returns oil to the pump l, constitute the power output elements ofthe torque converter, and these are the driving or input elements forthe planetary gearing. The reaction member R is represented bythe singlereactionblade 26.

The rst turbine T1 is connected by a central shaft 3l to a rear inputsun gear 35 of the planetary gearing. The second turbine T2 is connectedthrough a hollow shaft 32 surrounding the shaft 31 to a front input ringgear 37` which, to establish reverse drive, can be held by a device 38as will be explained. The turbine T3 is connected through a hollow shaft33 also surrounding the central shaft 31 and a neutral clutch 33A todrive the front carrier 40 and the rearfcarrier 42 of the plane- 3 Ytary gearing, 'which carriers are connected together and respectivelysupport front planetary pinions 44 meshing with the front input ringgear 37 and rear planetary pinions 46 meshing with the rear input sungear 35. The shaft 33 and the carriers 4t) and 42 form the principaldrive shaft of the transmission and are connected to the transmissionoutputY shaft 16. A `forward drive reaction ring gear 58 meshing withplanets 46 completes the rear planetary unit of the reduction gear, anda reac- Vtion sun gear 5t) meshing with the front planetary pinions 4t)completes the front planetary unit.

The rear reaction gear S8 may be held fast to establish drive from thefirst turbine T1 through the planetary reduction gear 35H46-58. To thisend the reaction gear 58 is connected to the hub or inner Vrace 62 of aninner one-way torque-establishing device having any suitable one-way orratchet members mounted inside of an intermediate hub 66 which forms theouter race of the inner one-way device. This is symbolically representedby the blade 64 fixed to the inner race 62 and overlapping the outerrace 66, which indicates that the race 62 can turn forward toward theeye of the `observer and away from the race 66 but cannot turn in theopposite direction. This is a symbolic representation Vof any suitableone-way torque-establishing device. The intermediate hub 66 forms theinner race for an outer oneway torque-establishing device represented-by the blade dit fixed to the intermediate race 65 and overlapping anouter race 75 which can be held against rotation by a device 72 whichprovides forward drive whenever the neutral clutch 33A is engaged. Theintermediate race on is connected to the front reaction sun gear 60 andmay be formed integral with it. The arrangement of the fone-way devicesis such that `when the forward device '72 is set, the hub 66 and the4reaction sun gear 60 are prevented from turning backward and the hub66, in turn, prevents the inner race 62 and the reaction gear 58 fromturning backward. In one-condition of operation, as willv be explained,the ring gear S8 turns forward while the reaction sun gear is heldstationary, and under another condition, both the ring gear and the sungear rotate forward. In reverse drive sun gear 60 is positively drivenbackward by the ring gear 58 through the one-way device 62-64-66,forward device 72 being released, as will be explained.

Heretofore the various definitions of the terms clutch and brake havecaused confusion. Some attempts to define the terms have been based onuse or function regardless -of structure while others have ybeen basedon type of structure or arrangement regardless of use or function. Thishas sometimes led to definitions of clutch and brake being mutuallyexclusive where they should not be and has led to overlappingdefinitions where mutual exclusion was intended. None of thesedefinitions which have come to my attention have satisfactorily takencare of the situation in which an identical specimenis sometimes -abrake and sometimes a clutch. Neither do they adequately describe asituation in which it is immaterial whether a member is a brake or aclutch, as described by reference to structure, where the significantconsideration is the function of the device regardless of its structure.

To avoid this confusion and indeniteness, the term torque-establishingdevice is used Vherein generically to mean any disengageable devicewhich can be engaged to prevent rotation between two members which areotherwise relativelyV rotatable.r l-f both members are rotatableabsolutely, the device when engaged forces them to rotate at the samespeed so that one member can drive the other. On the other hand, if oneof the members is fixed, then engagement of the device holds the othermember fast, in which case the generic device may be specificallydefined as one form of brake or lock. Where the device prevents relativerotation between two members inr one sense of rotation but permitsrelative assenso, Y p

rotation in the opposite sense, then the device may be sub-genericallydened as a one-waydevice or ratchet device or freewheeler which termsare used to mean any device between two relatively rotatable membersVwhich permits therst member to rotate in one sense with respect to thesecond member ibut prevents the iirst member from rotating in theopposite sense with respect to the second member; that is, it locks thetwo members together. If both members are rotatable absolutely, thefreewheeler is a one-way drive clutch. If one of the members cannotrotate, the freewheeler becomes a oneway brake.

' These definitions are adapted in View of the custom of engineers ofreferring to a clutch as anything which engages to establish driveorchange ratios, and referring to a brake as something which retards thevehicle.

peraton of general arrangement For normal forward driving, the Vforwardtorque-establishing device 72 is set, the neutral clutch 33A is engaged,and all other torque-establishing devices are released, as shown in Fig.2. On starting, the inertia of the car holds carriers 4t), 4t2 and theturbine T3 stationary. Oil from the pump l, rotated at suitable speed,exerts torque on T1 to drive the rear input sun gear 35 forward, whichbecause the reaction gear 5S is held by forward device 72 and the twoone-way devices iti-63.436 and 66- titi-62, drive the output shaftforward at reduced speed, multiplying the torque supplied by turbine T1by the ratio of the gearing 35-46-S. This necessarily also positivelydrives the turbine T3 forward regardless of hydraulic conditions in the,torque converter because I3 is positively connected to the output shafti6. in addition, oil owing from T1 to T2 exerts torque on T2, whichthrough shaft 32 drives the front input ring gear 37 forward, tending torotate the front pinions 4d forward. When ring gear 37 rotates fastenough this tends to rotate the front reaction sun gear 6i? backward,but this is prevented by the outer vone-way device 71?63-66 and, infact, the front sun gear has previously been locked by the rear reactiongear 58 and the two onefway devices as described. Consequently, thefront ring gear 37 adds to the drive the torque of T 2 multiplied' bythe ratio of the front planetary gear set ii--di-S On starting the carand below some definite speed, depending upon the design of the bladesof the torque converter, the turbine T3 may not exert any significantpositive or forward torque derived from hydraulic action but, aspreviously stated, it is positively driven by the carriers. However, atsome definite speed ratio of input shaft to output shaft, positivehydraulic torque is impressed on T3 and its speed, due to hydraulicaction, tends to exceed the speed of the carriers as driven by the otherturbines. At this point T3 assists in driving the car by torque exertedon the main drive shaft 33-33A--16- As the speed of the carprogressively increases from standstill, two things happen successively.First, the torque delivered to the output shaft by T1 through the rearplanetary units drops to a vanishing point as T1 reaches its terminalspeed. Meanwhile the speed of T2 increases. Whenthe speed of T2multiplied by the ratio of the front planetary unit, exceeds the speedof T1 multiplied by the ratio of the rear planetary gearing, T2 .isdriving the carriers faster than T1 can drive them and the innerfreewheeler 66-64-62 breaks away. Then the rear reaction gear 58 rotatesforward and T1 idles in the oil stream. T2 is now driving the car andmay be assisted by T3. Second, upon further increase in the speed of thecar, T2 reaches its terminal speed and can no longer drive the carriersdil-42 through the front planetary as fast as T3 can drive them, T3being directly connected to the carriers. T3 alone then drives thecarriers, the outer freewheeler l'i-o-o breaking away and the sun gear60 turning forward while Tzidles in the stream of oil. A Y Y For reversedrive, the neutral clutch 33A is engaged, the forward device 72 isreleased, and the reverse device 38 is set to hold the front ring gear37 as a reaction gear, as shown in Fig. 2. Incidentally, this holds T3stationary during all reverse drive. Now, T1 drives the rear input sungear forward which, because carrier d2 is initially held stationary bythe car, drives the ring gear SS backward and, through the inner one-waydevice 6664-d2, drives the front sun gear backward. This is permitted,in fact, for although the outer one-way brake 7d-6d6 tends to lock, itsouter race 7@ can turn backward, being unopposed by the released forwarddevice 72. Consequently, the front sun gear d@ rotating backward drivesthe carrier di? slowly backward, carrying the turbine blade T3positively backward. ln fact, it is possible depending on blade design,for the turbine T3 to have reverse torque impressed on it hydraulically,in which case it will assist in driving the car backward. The turbineT2, being held stationary in reverse drive, acts as a guide wheel orreaction member directing oil from T1 backward against the forwardlyfacing sides of the blades of T3, causing them to drive the carriersbackward.

In order to place the transmission in neutral, all of thetorque-establishing devices are released, as shown in Fig. 2. Underthese conditions T1 can exert no torque on the output shaft d@ becausethe forward device 72 lets the planetary gears 4d spin the ring gear d8idly. The turbine T2 can exert no torque on the output shaft 16 becausein driving the ring gear 37, the planetary gears di? spin the reactionsun gear dit freely backward since this gear is not held by the device72,. The third turbine T3 can eirert no torque because the neutralclutch 33A is not engaged.

lt has been observed that when the car is set for drive, the turbinessuccessively pick up the drive and thereafter exert torque atprogressively decreasing ratios and that the car eventually becomesdriven by the third turbine alone under conditions which aresubstantially hydraulic coupling, providing substantially one-to-onedrive. If it is desired to drive the car at a low speed ratioindefinitely, the rear reaction gear 53 is positively held by a device74 and all other torque-establishing devices are released, as shown inFig. Z. ln these conditions the rst turbine T1 drives the rear input sungear T15 which, because the ring gear 5b is held, drives the carrier l2and output shaft 16 `forward at a speed which bears a constant ratio tothe speed of the turbine T1, this ratio being determined by the rearplanetary gear set. The turbine T 1 cannot become disengaged from thedrive because the reaction gear 5S is prevented from freewheeling. T2cannot have any effect on the drive because, altho it drives ring gear37, there is nothing to hold the reaction gear 6d, device 72 having beenreleased. Consequently, under these conditions the car remains drivensolely by T1 in a definite range of speed ratios with respect to T1.

This arrangement is also useful to retard the car going down grades.Device 7d is set and all other torqueestablishing devices are released.T2 and T3 are effectively disconnected from the output shaft 16, asexplained above, and the output shaft drives the carrier l2 whenever thecar tends to drive the engine. This overdrives the turbine T1; that is,it drives the turbine T1 faster than the output shaft by the ratio ofthe planetary gear set -Jle-SS and at this high speed, the turbine T1tends to become an impeller, transmitting torque to the impeller blades2b which are held to a slower speed by the engine and so oppose movementof the car.

The transmission may have any suitable parking lock or brake such as agear or circular flange secured to the carrier d2 or output shaft 16 andhaving peripheral teeth 76 which can be locked by a dog 73 secured tothe frame.

Structure Figures 3 and 3A illustrate one form of actual structureembodying the invention including the elements and their mode ofoperation disclosed schematically above.. Referring first to Fig. 3, theengine shaft '10 is bolted to a flywheel 1G@ which is bolted to a torqueconverter casing including an impeller shell 102 and a front cover 16d.The blades 1li are attached to the irnpelicr shell hr2 and to an innershroud 165. The space between the shell and the shroud forms the paththrough the impeller for working liquid, as is known. In the center ofits rear end, the impeller shell 102 is welded to or formed integralwith a tubular shaft 106 which drives any suitable oil pump 1% hereincalled the front pump. The shaft litio is surrounded by any suitableseal 11i) which prevents leakage of oil from the torque converter intothe dry space 112 which encloses the torque converter and is enclosed bypart of the transmission casing 113.

The shaft 106 is spaced from the stationary reactionV sleeve 99 to forma passage 114 by which oil may be supplied to the torque converter fromthe system asis known.

The rst turbine T1 includes an outer supporting shell 116 and an innershroud 11d between which the blades 21 are fixed in any suitable manner.is riveted at its center to a flange 12b which may be keyed to the frontend of the innermost shaft 31 which drives the sun gear 35, as shown inFig. 1. The flange 12d may be provided with any suitable number ofopenings 122 for passage of oil for equalization of pressure betweenopposite sides of the T1 shell 116. The T1 assembly may be balanced bybalancing pins 123 (for example three in number about the periphery)which may be positioned radially and held in any suitable manner. TheVfront end of shaft 31 is supported by a radial bearing 12d and a thrustbearing 126 of any suitable form in a cap 123 formed in the front cover104.

At its rear end, the first turbine shaft 31 is supported in a bearingsleeve 132 in a bore in the front end of the output shaft 1d. The inputsun gear 3S, shown in Fig. l, is keyed to the rear end of shaft 31 asshown in Fig. 3A.

The third turbine T3 has an outer shell 146 and an inner shroud 142between which the blades 2-3 are xed. The outer shell is riveted to aflange 144 keyed to the shaft 33 which forms part of the main driveshaft of the transmission. At its front end the shaft 33 is supported bya radial bearing sleeve idd and a thrust bearing 143, both of anysuitable form and mounted in counterbores in the T1 hub 12d. While thethrust bearing 148 may be of any suitable form, it is preferably of theconstruction and arrangement disclosed in the application, S.N. 586,-A

116 for U.S. patent tiled by me on May 21, 1956, now US. Patent No.2,854,300. At its rear end, as shown in Figs. 3 and 3A, the shaft 33 iskeyed to one member of the neutral clutch 33A and its operatingmechanism. This includes the clutch drum 150, keyed to the shaft 33, andhaving keyed to it a clutch cone 152 (Fig. 3A). i

The drum carries a sliding piston 154 forming with the drum anexpansible chamber 156 to which oil under pressure can be admitted tourge the piston to the right, as Fig. 3A is seen, against the force of awaved return spring 1523. A cone 16h is formed on the right-hand face ofthe piston, which cone with the previously mentioned cone 152 formsdriving clutch elements between whichthe driven clutch cone 162 may begripped when fluid under pressure is admitted to the cylinder 156. Theclutch cone 152 is keyed to the front planetary carrier 4b. When thisclutch is engaged, the turbine T3 is connected to the output shaft 16.The rear end of the shaft 33 may be supported on the shaft 31 by abearing sleeve 16d.

The second turbine T3 includes an outer shell 176 and an inner shroud172 between which the blades 22. are

tired in any suitable manner. The inner shroud 172 may be mounted on ahub 174 which is supported by a spider 176 on an inner hub 173 keyed tothe front end of the T3 shaft 32 and supported axially from the hub 144by The rr1 Shen irs assenso a thrust bearing 180 like bearing 148supports in a counterbore in the hub 144. The spider may be constructedin any suitable manner, for example as shown in the application for U.S.patent of Kelley and Lindsay, SN. 478,118 led Dec. 28, 1954, or theapplication of Kelley Ser. No. 537,472, led Sept. 29, 1955. The secondturbine T2 is supported radially by a radial bearing sleeve 182 betweenthe front end of shaft 33 and the front end of shaft 32. The blades 22,outer shell 176, inner shroud 172, and hub 174 can be cast as a singleintegral structure if desired. The outer face of the shell 17% may beprovided with grooves 184 to form a labyrinth seal with the T1 shell116. The hub 178 may have openings 186 or ducts formed through it, andthe front end of the shaft 32 may have openings 188. These openings,with the space inside the hub 178,- form a passage from the interior ofthe torque converter to the annular space 1% between the hollow shafts32 and 33, which passage forms an outlet for oil from the torqueconverter, as will be explained. -1

As seen in Fig. 3 the rear end of the T2 shaft 32 may be welded to adrum 192 to which is attached the front input 'gear 37 shown in Fig. 3A.To the drum 192 is also splined the conical drum 38, which correspondsto the device 38 in Fig. l and can move axially with respect to the drum192 to be gripped between a stationary cone 194 and a non-rotatable cone196 forming part of aV piston 198 sliding in a stationary annularcylinder 26th fixed to the frame 113. The piston defines a pressurechamber 202 within the cylinder 200' to which oil under pressure may beadmitted from the control system as will be explained to push the pistonto the right as Fig. 3 is seen to engage three cones 195, 38, 194. Thepiston 198 may be urged to the left to disengage the cones by a wavedspring 284. The rear end of the T2 shaft 32 may be supported radially bya bearing sleeve 286` on the drum 1150 and it may be supported axiallybetween thrust bearings 208 bearing against the cylinder 2th? and theVdrum 150, respectively.

Referring to Fig. 3A, the front carrier ttl includes a front anige 250which may be integral with a carrier sleeve 252, a rear flange 254 andthe connecting spindles 256 on which the planetary gears 44 are mounted.The neutral clutch drum 162 is keyed to the front flange 25). The sleeve252 is supported for rotation onibearing sleeves 258 on shaft 31 and itsrear end is keyed to a tubular extension on the front llange 262 of therear planetary carrier 46. The flange is held against axial movement tothe left by a snap ring 263. The carrier 42 is completed by the rearange 264 and spindles 266 carrying the planet gears 46. The rear flange264 may be formed integral with the output shaft 16 and is pro- Vvidedwith the previously mentioned parking teeth 76 which may be engaged byany suitable parking lock or brake to prevent rotation of the outputshaft 16.

Any suitable form of oil pump 270 is keyed to the output shaft 16 forproviding oil under pressure in response to forward rotation of the caras is customary. The output shaft 16 isr supported in the casing 113 byany suitable radial bearings 272 and thrust bearing 27d.

The sun gear 35 may be supported axially between the flanges 262 and 264by thrust bearings 27e and 278. Either or `both of these may be likebearing 148.

The sun gear 6G is formed integral with a flange Ztl formed integralwith the intermediate race 66, this structure being `supported forrotation on bearing sleeves 282 ony carrier sleeve 252. The sprags 68corresponding to the diagrammatic ratchet member 63 of Fig. 1 are sumported between the intermediate race 66 and the outer race 70, to whichis splined the conical drum 72, which is the forward device 72 of Fig.1.

The inner race 62 of the inner free-wheel device 6'2-64-66 is formed asa sleeve integral with a ange 290 to which the ring gear S8 is keyed.The ring gear is'held axially on the ange 290 by a snap ring 292. The

sleeve 62 is mounted forrctation on a bearing sleeve 294 mounted on thetubular extension of the carrier flange 262, and is supported axiailybetween a thrust bearing Y 2% which bears against the ilange 262 and bya thrust bearing 298 which bears against the sun gear 6@ which in turnis supported axially by a thrust gearing 388 bearing against the flange25d, the other side of which is supported axially by bearing 362 whichbears against` piston a pressure chamber 318 to which fluid underpressure may be admitted from the control system to urge the device .312to the lett against-the force of a restoring spring 319 to engage thecones 3118-72-312 to hold the outer race 75l fast. The cylinder 314iextends to the right beyond the piston 316 and is sealed by an end 326keyed to the cylinder and forming with the piston and cylinder a secondpressure chamber 322 to which fluid may be admitted by the controlsystem to urge the end and the cylinder to the rightas Fig. 3A is seen.The end 320 carries a stationary non-rotatable brake member 324 splinedto the casing. Movement of the brake member 324i tothe right engages astack of friction members, namely the driven brake. discs 326 splined tothe ring gear 58, thenon-rotatable brake member 328, and the shoulder338 formed in the casing 113. ring gear 58 for hill braking.

In transmissions of the type disclosed herein there has been failure ofone or both of the overrunning devices 62-64--66 and 66--63--751 In onewell-known form of overrunning device the ratchet or one-way members arerollers such `as 86 in Fig. 3, placed between an inner circular race andan outer race provided with sloping cam surfaces, individual energizingsprings urge 'the separate rollers toward the narrow ends of the spacesbetween the cams and the inner race so that if the inner race tends torotate toward the narrow ends of the spaces, thel rollers wedge the tworaces together and lock the clutch.V V1f the inner race tends to rotatein the opposite sense, Vthe friction between the inner race and therollers tends to carry them toward the wide ends of the spaces and thispermits the inner race to rotate freely with respect to the outer race.In another form of overrunning device the ratchet members are spragssuch as are indicated at 64 and 68 in Fig. 3A. These are placed betweentwo circular races and are urged into nearly radial position in contactwith both racesby some form of energizing spring, frequently a garterspring or a continuous coil spring that surrounds all of the sprags. Thesprags form struts which-when properly positioned, transmit force fromone of the races to the cther when one race tends to rotate in one sensewith respect to the other and so locks the races together. However,tendency to rotate in the other sense causes the sprags to swing` out oflocking position and let the races rotate freely with respect to eachother. i

With either of the above formsV of overrunning device, if one raceshould be rotated While the'outer race` is not held, 'the force of thelenergizing springs holds the ratchet members in contact with broth racescausing sui- K This holds the Assume thatA the inner race is rotating inthe direction or sense of rotation which tends to lock up the clutchwhen the outer race is held and lthat the outer race is free and thatnearly all of the -ratchet members have been thrown out of contact withthe inner race by centrifugal force. Assume also that the outer race isnow stopped, while theinner race continues to rotate. As the outer raceslows down approaching the stop, the ratchet members will be moved intocontact with the inner race by energizing springs, but because the forceof thel springs on the separate ratchet members varies, the ratchetmembers will move into contact with the inner race and tend to lock atdifferent times.` I believe that these successive attempts to lock bythe ratchet members have caused various kinds of failures which havebeen noted in overrunning clutches in this formof gearing. One exampleis breaking of sprags. For example, consider the condition when theengine is idling fast, as in warming up while the car is standing andthe neutral clutch 33A is disengaged. The carriers 42 and 46 are heldstationary by the `drive wheels. T1 is driving sun gear 35 so that thering gear S8 carrying the innermost race 62 is rotated backward,carrying with it race 66, to rotate the outermost race 70 backward. Withparticular overrunning devices which have been used, it has been foundthat rollers and sprags between races 66 and 70 will move out of contactat engine idling speeds of above 1400 r.p.m. which speed frequentlyoccurs.

Assume that under these conditions the forward device 72 is engaged toput the transmission in forward drive. This rapidly slows down and stopsthe device drum 72 and simultaneously exerts considerable torque on theoverrunning device 66-68-70. If such torque is exerted while only a fewof the ratchet members are disengaged, trouble results. If rollers areused, the races may be distorted and `forced out of concentricity. Ifsprags are used, the sprags may be broken or the races may betemporarily sprung out of concentricity or the sprags may turn over,slip or lock up so that they will not release.

It is one of the objects of this invention to overcome the diiicultiesjust described by constructing the overrunning devices so that theratchet members remain in con tact with both races under all conditionswhich can occur in the operation of the transmission so that when eitherof the inner races is driving either of the outer races `and torque issuddenly applied to the overrunning device by stopping the outer race,all of the ratchet members lock the same time, enforcing concentricityof the races and distributing the torque among all of the ratchetmembers substantially equally. One way of accomplishing this is showninFigs. 4 to 7, inclusive.

The sprags 64 and 68 `are identical, consequently only one will bedescribed. Each sprag includes an outer cylindrical surface 35i? whichis not necessarily circular and which bears on the outer race 70, and aninner cylindrical surface 352 which may not be circular and which bearson the inner race 66. Each sprag has one flat face 354 and an oppositeface having a ridge or projection 356. The sprags are assembled in acage 357 which includes a pair of side cheeks 358 joined by a number ofintegral bars 361) spaced about the cheeks to leave windows, in whichwindows the sprags 68 are assembled. The bars 360 are of the samegeneral cross section as that of the sprags 68. Each sprag is cut awayat each end to form a shoulder 362 which is `supported on a ledge 364formed on the cheek of the cage. The sprags and bars are notched at thecenter as at 366 to receive a garter spring 368 which forms theenergizing spring and urges the sprags into contact with both races 70and 66. Preferably from two to four sprags are assembled in each windowand all ofthe sprags are urged in one direction against the end of thewindow by an accordion spring 370 placed in each window. As shown inFig. 5, the center of gravity of each sprag is at the point 372. Thesprag acts as if its mass were concentrated at this point and when thedevice is rotated, tends to move it in the direction of the arrow 374.The point of contact between the sprag and the race 70 is at the pointof the arrow 37 6, and the supporting force of the race 7o againstrotation on the sprag acts at this point. Consequently, there is amoment due to rotation of the device as a whole which tends to rotatethe sprag clockwise about the point of the arrow 376 and this constantlyurges the surface 352 into contact with the race 66. Therefore, nomatter how fast the races are rotated there is no forced tending to movethe sprag 68 out of contact with the inner race.

The accordion springs 37@ extend across the length of the sprag, asshown in Fig. 6, and resiliently urge all of the sprags toward the bars36d. The ilat face of the irst sprag contacts the ridge of the bar andthe flat face of each sprag contacts the ridge of the preceding sprag,so that all of the sprags are resiliently held parallel to the axisagainst the bars 360. This prevents twisting of the sprags in operationand reduces likelihood of breakage.

The outer cage 357 may be held in the outer race by a pair of snap rings378 and the inner cage 357 may be held against the flange 2S!! by snapring 386.

I claim:

1. A power transmission comprising in combination a first planetarygearset including an input gear, a reaction gear, and planet gearsmounted on a carrier connected to an output shaft; a second planetarygearset including an input gear, a reaction gear, and planet gearsmounted on a second carrier connected to the tirst carrier, means forrotating the rst input gear forward, means for rotating the second inputgear forward, a rotatable ring member, means for at times holding thering member against rotation, a second ring member locatedconcentrically inside the iirst ring member, and connected to the secondreaction gear, one-way torque-transmitting elements between the ringmembers, a third ring member located concentrically inside the secondring member, one-way torquetransmitting elements between the second andthird ring members, and means for selectively holding the first ringmember to prevent backward rotation of the reaction gears or releasingthe first ring member for backward rotation, the transmission includingmeans for positively holding said one-way torque-transmitting elementsin contact with both ring members between which they are located inspite of revolution of said one-way members about the axis of the ringmembers.

2. A power transmission comprising in combination a tirst planetarygearset including a sun gear, a ring gear, and planet gears mounted on acarrier connected to an output shaft; a second planetary gearsetincluding a ring gear, a sun gear, and planet gears mounted on a secondcarrier connected to the first carrier, means for rotating the first sungear forward, means for rotating the second ring gear forward, arotatable ring member, means for at times holding the ring memberagainst rotation, a second ring member located cencentrically inside ofthe first ring member and connected to the second sun gear, onewaytorque-transmitting elements between the ring members, a third ringmember located concentrically inside of the second ring member, one-waytorque-transmitting elements between the second and third ring members,and means for selectively holding the rst ring member to preventbackward rotation of the first ring gear and second sun gear orreleasing the first ring member for backward rotation, the transmissionincluding means for positively holding said one-Way clutch elements inContact with both ring members between which they are located in spiteof revolution of said one-way members about the axis of the ringmembers.

References Cited in the le of this patent UNITED STATES PATENTS

